Method for killing plants



United States Patent METHOD FOR KILLING PLANTS Lewis Edward Goyette, Richmond, Va., assignor to Virginia-Carolina Chemical Corporation, Richmond, Va., a corporation of Virginia No Drawing. Application February 14, 1957 Serial No. 640,093

'3 Claims. (Cl. 712.3)

growth of undesirable plants.

Chemical plant-growth substances are. substances.

which afiect the growth of one or more of the plant forms including seeds, germinating seeds, seedlings, immature plants and mature plants. The growth-affect may be inhibition, retardation, acceleration or killing. In the last instance the substance is known as a herbicide.

vChemical herbicides are classified generally according to the type of activity they possess. A given compound may possess more than one type of activity and its action may change with a change in application rate. Any compound which shows slight activity at a low rate of application will show more activity at a higher rate.

The activities are generally classified as follows:

1. Preemergencea. Non-selective I b. Selective 2. Postemergencea. Non-selective b. Selective Preemergence herbicides are applied to the soil before the seed germinates. The compound, to be e'fiective, should work in one or a combination of the following ways,

(1) Penetration into the soil should not be far enough to contact the crop seed if the compound is phytotoxic to them.

(2) The compound should be decomposed before the crop seed germinates if the compound is phytotoxic to the germinated seed.

(3) The compound should be selective, i.e., it should kill unwanted seed or seedlings but not harm the crop seed.

Some compounds are elfective preemergence herbicides even though-they are phytotoxic to all seeds. This is because crop seed are generally planted deeper than contact herbicide.

2,927,014 Patented Mar. 1, 1960 The most eifective preemergence herbicide is the selec tive one. If the compound will kill seed, germinating seed and seedlings of the unwanted weeds but do no harm to the seed, germinating seed or seedlings of the crop, then there is no danger from over-penetration. The crop is thus allowed to germinate and grow and the unwanted weeds are killed.

Postemergence herbicides are applied after the crop and weeds have obtained substantial growth. A nonselective postemergence herbicide is called a general That is, it kills any plant form that r it contacts if the dosage is sutficient.

Selective postemergence herbicides do not harm the crop but kill the weeds. They may be divided into two classes:

(1) Those which are selective on a rate basis, i.e. phytotoxic to weeds but not the crop at a low rate, but phytotoxic to both at a higher rate.

(2) Those which are inherently selective. These com pounds show no harm to crops at any reasonable rate but kill weeds at reasonable rates of application.

. Most compounds that are found to have herbicidal activity are non-selective. That is, at a given application rate, the compound is just as liable to kill the crop as it is the weeds. It is only rarely that a selective compound is found.

Generally, selectivity is between broad-leaved and narrow-leaved plants. Both of these classes contain weeds and crops. Thus, in a broad-leavedl crop at selective compound would kill narrow-leaved weeds but would allow broad-leaved weeds and the crop to grow. The

opposite is true of a compound selective to narrow-leaved plants.

Some compounds, however, exhibit specific selectivity for a certain plant. If this plant is a crop plant, then the compound is highly valuable. The ideal compound would be one selective to all crops but phytotoxie to all weeds. r

The present invention relates to the use of compounds of the general formula in which R and R each represent radicals selected from one inch. Unwanted weeds generally will germinate only from seeds that are close to the surface. Thus,

a compound of lowpenetration would kill seed in the the group consisting of alkyl, aryl, alkaryl, aralkyl, substituted aryl and substituted aralkyl radicals and X and Y are positive whole numbers whose sum is 3. These compounds may be divided into two groups (1) the phosphonates in which X is 2 and Y is 1 and (2) the phosphinates in which X is 1 and Y is 2; I have found generally that both the phosphonates and. the phosphinates kill i.e. that they are herbicides with respect to germinating seeds, seedlings and plants, both mature and immature and that they'difier from each other only with respect to seeds i.e. the phosphinates also kill seeds whereas the phosphonates do not kill seeds. This invention therefore embraces the use of the phosphinates as herbicides for "all ofthe plant forms and the use of both the phosphonates and the 'phosphinates as herbicides for all of the plant forms excepting seeds.

The foregoing general statements are based upon and supported by the following experimental data.

METHOD OF TESTING are sub-irrigated for 24 hours prior to application of the 15 st' tompou The compound'is =applied-atthe rate of '16 lbs. per

Turnip and rye grass seed are used to simulate 10 t 4. 7 acre after being dissolved in a xylene-Atlox mixture. Results are taken seven to'ten days after application.

By counting the number of weeds in a healthy condition and comparing to an untreated planting, a percent control is obtained.

The Word Atlox used above is the registered trademark of Atlas Powder Co. and is applied to a series of surface-active agents,i.e. emulsifiers and wetting agents adapted for use with agricultural chemicals including insecticides and herbicides.

(b) Pstemei'gence.The planting is the same as for preemergence. The plants are allowed to grow for ten days. The test compound is then sprayed on the foliage at an approximate rate of 2 lbs. per acre. After seven to tend days results are taken. A visible estimation of the degree of phytotoxicity is recorded as dead, severe, moderate, slight or none.

Table l PREEMERGENCE AND POS'IEMERGENCE RESULTS WITH DIALKYL ALKYLPHOSPHONATES Preemergence Postemergence' Results Compound Results No. R Group B Group Turn. R.G. Turn. "R.G. Corn Cotton 0 0 Moderate. Moderate Moderate- Moderate. 50 50 S1 ht S1 Slight, 85 37 85 92 37 I Mod. Sev- 50 Dead.

0 Mod. Sev Severe, 19 as S ev'ere Mod.

PREEMERGENCE AND POSTEMERGENCE 13.128252? IWZVITH PHQSPHONATES OTHER THAN DIAIJKiYL o t 1; (R!) V Preemergence p I Results, Per- Postemergence Results Compound No. B Group R Group cent Killed.

Turn. 1m. Turn. 1m. Corn Cotton allyl allyl O 0 Mod Slight. I 2-bromoethyL. 2-bromoethyl 0 0 Moderate... Moderate ethy pheny 50 'Sev.-Dead N 3,4-dich1orobe11zyl 0 Slight 2,4-dichlorobenzyl 50 50 do 15 20 l-naphthylmethyl..- 1 0 1 0. Z-(lfi-gaphthyl) 0 0 e y i .-do.- trichloroac'etyl 72' 41 Sli h Slight .Do. 2-butoxy'ethyl. 2-butoxyethyl 0 0 Dead Mod Sev MorL-Sev.

Table III w i PREEMERGENCE AND POBTEMERGlNCE RESULTS WITH PHOSPHINATES mo mo,

Preemelrlggnce Postemergence Results es 7 Compound No. B. Group B Group Turn. R.G. Turn. R.G. Corn Cotton butyl. 56 7 7 Slight--. Slight Slight.

do 64 45 Dead...- M Mod d. d 100 75 do Dead- Do. do i 83 56 -do. --do Dead. 2-ethylhexyl.. 96 82 do do Do. do 42 51 do do Do. do 0 0 d o- Sew-Dead..- None. 1-butylamino'2- 20 do ead Dead J ethylhexyl octyl. phenylZ-ethylhexyl 0 0 do Dead Mod.-Sey. bu tyl. 33 13 ..do Sew-Dead.-. Sen-Dead. i ls'obnfi y 1 00 80 do.-. None Mod-Se Dead.

When a compound has shown good activity at the initial screening concentration, it is retested at one-half the original rate in the postemergence test. The fo1low-- ing results were obtained with the phosphonates in re testing.

Table IV Compound No. Turnips Rye Grass Corn Cotton Dead--- Mod.l-. Sll ht Sev----- Dead- Slight If the compound still has good activity at this lower rate, it is then tested in the field. Various weed seed of broad leaf plants .andlligrasses at these respectively 90% and 100%.

ratess were,

Several of the phosphinate compounds were retested at V 25 one-half the original rate for postemergence activity. The

results were as follows:

Table VI Compound No.

Turnlps Rye Grass Corn I do .e..do Dead are planted as well as crop seed. After the plantings 51 have obtained substantial growth, they are sprayed with the test compounds. The following results were obtained 40 for postemergence application of the compounds listed.

t Table V l Percent Control 1 F' Com d LbsJ Ragweed, Corn Cotton Soybeans Peanuts o 0. Am Mustard, Rye Grass Lam and Other Quarter, Grasses Turnlps 4 25 Bligh Mod Mod-Slight-.- Deed-Sew 8 50 Mod-Slight-.- Sev Dead-Sev"--- Dead. 8 90 50 do-- Sev. DPad Do. 4 50 50 Sev- Dead-Mod Sev. 8 75 SewMod-.- Mod Sevl-Mod 4 25 0 Mod filipht Slight. 8 75 25 Dead-Mo do Do.

1 Visual estimates.

The compound No. 9 was tested as a general contact herbicide at rates of 20, 40 and lbs./acre.x Control 60 Compound No. 27 was tested in the field for postemergence activity. The 4 lbs./ acre rate was made on two plots.

T able VII Percent Control Degree of Damage 1 Compound N0. Lbs./ Ragweed,

Acre Mustard, Rye Grass Lambs and Other Corn Cotton Soybeans Peanuts Quarter, Grasses Turnips 2 50 0 None Mo Sev Dead. 27 4 75 50 Slight-None.-- Dead-Sev-.. Dead-Sev--. Do.

""" 4 75 75 Mod Mod Dead-Mod" Sev.-Mod.

8 75 Mod Dead-Sev--. Dead-Sev-.- Mod.

1 Visual estimates.

2,927,014 a; a E Several of the phosphiinate compounds were tested at Table X low rates for preemergence' activity. The results are given in the table below.

1,000 p.p.m. 500 p.p.m. 100 p.p.m. Table VIII g Turnlps Rye Turnips Rye Turnlps Rye Percent Control Grass Grass Grass Compound No. Lbs/Acre '19 53 66 24 1a 7 Turmps Rye Grass 82 72 68 31 19 16 94 100 100 100 25 s 8 100 82 93 66- 66 60 s 26 4 75 38 100 100 99 95 83 e0 8 100 96 100 100" 100 100 s5 43 25 4 90 56 as 59 29 33 4 s .3 I 8 6o a a a :2, t 4 V 50 47 21 2 7 Compound 27 was tested for preemergence activity in the field. The results were as follows:

Ta'ble IX I claim: 1 V 1. A method for undesirable plants which com.-

The results in the following Table X show the effect of some of the phosphinate compounds on seed germination. In each test 25 rye grass and 25 turnip seed were used. Several milliliterss of a solution of the test compound in an organic solvent was placed in a Petri dish. The solvent was evaporated. Fifteen ml. of water was then added. Enough of the organic solution was used to give concentrations of the compound of 1000, 500 and 100 ppm. in the 15 ml. of water. placed in the dish and the seed were added. The dishes were covered and held at 28 C. for 96 hours. Each compound was tested in four dishes and four untreated controls were used. Results were taken as percent inhibition of germination compared to the untreated controls. l

4.0 Filter paper was prises contacting the plant at any stage of its growth with a herbicidal amount of a compound selected from the group represented by the formula.

wherein-R and. R represent alkyl groups each, containing from 2 to 8' carbon atoms and X and Y are positive Whole numbers Whose sum is 3.

2. A method as defined in claim 1 in which X is 1 Y is 2- 3. A method as defined in claim 1 in which X is 2 and Y is 1.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Zimmerman, in Indus, and Engr. Chem. May 1943, vol.

35, No. 5, pp. 590 to 601.

Crocker: Growth of Plants, 1948, page 226. Pastac et al. in Chemical Abstracts, vol. 49, col. 1878(b), 1955, and column 14110(c). 

1. A METHOD FOR KILLING UNDESIRABLE PLANTS WHICH COMPRISES CONTACTING THE PLANT AT ANY STAGE OF ITS GROWTH WITH A HERBICIDAL AMOUNT OF A COMPOUND SELECTED FROM THE GROUP REPRESENTED BY THE FORMULA 